Coil Flow and Pressure Drop

2 posts / 0 new

Hi everyone,

I am looking for confirmation I understand what eQUEST is doing with inputs
for VAV boxes with HW reheat coils.

On the water side for each. reheat coil, I know design flow, design delta
T, design heat gain and design pressure drop.

Based on the below inputs, I am assuming eQUEST will calculate the design
flow ~ 1.9 GPM; [9,625 Btu/hr / 500 / 10 degF = 1.9 GPM].

[image: Inline image 5]

On the air side, I also know the design flow and delta T. For this
example, it is 270 CFM and 25 degF:

[image: Inline image 4]

Will eQUEST use the max airflow (270 CFM) and subsequently calculate the
max heat gain across the coil (~7,290 Btu/hr); [1.08 * 270 CFM * 25 degF =
7,290 Btu/hr].

If so, does eQUEST adjust the HW flow rate through coil to match this heat
gain (~1.46 GPM); [7,290 Btu/hr / 500 / 10 degF = 1.46 GPM]

Am I correct in how eQUEST is using these inputs?

Also. how does eQUEST calculate the PD through the coils, both on the
water-side and air-side?

Thanks
Darryl

Aug 30, 2016

via Equest-users

Offline

Joined: 2016-07-15

Reputation: 400

Hi Darryl,

It seems that the 25 degree F and delta T 10 degree F are seeming to be
correct.
But as far as i know the AHU part has lesser load and capacity as there can
be some transmission or heat losses as far as my knowledge.

The chiller piping has lesser heat losses through the circulation loop.
The delta T on room side can vary and match to optimum.
Always i have found that chiller has higher load as compared to air side.
One can measure the pressure differential with the help of venturimeter ,
manometer or pitot tube or differential pressure measurement meter.

Thanks,
Sharad.Kumar

Today's Topics:

1. Coil Flow and Pressure Drop (Darryl Kasun via Equest-users)

---------- Forwarded message ----------
From: Darryl Kasun via Equest-users
To: equest
Cc:
Date: Tue, 30 Aug 2016 11:28:22 -0700
Subject: [Equest-users] Coil Flow and Pressure Drop
Hi everyone,